Mixed tower self-repairing steel-concrete connection structure based on gradient stiffness matching and SMA constraint and wind power mixed tower

Abstract

The invention provides a mixed tower self-repairing steel-concrete connecting structure based on gradient stiffness matching and SMA constraint and a wind power mixed tower. The mixed tower self-repairing steel-concrete connecting structure comprises a top ring duct piece and a switching structure connected to the upper portion of the top ring duct piece. The top ring duct piece is a prefabricated concrete annular segment, and an SMA constraint component is pre-buried in the top ring duct piece and used for self-repairing cracks in the top ring duct piece; a shell of the switching structure is an SMA plate, high-strength concrete is poured into an inner annular cavity to form a composite structure, an SMA non-resonant honeycomb structure with the elastic modulus similar to that of the concrete is arranged at the position of an inner skirt edge, and through cooperation of the SMA plate and the SMA non-resonant honeycomb structure, the rigidity difference and the deformation difference under the temperature are weakened, and force transmission is optimized. By means of the technical scheme, the problems that in the prior art, due to mismatching of the rigidity gradient of the steel-concrete switching section and the duct piece interface, the axial stress concentration external expansion effect is caused, and the anti-cracking performance of the duct piece is degraded in the operation stage of the mixed tower can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power tower structures, and in particular to a hybrid tower self-repairing steel-concrete connection structure based on gradient stiffness matching and SMA constraints, and a wind power hybrid tower. Background Art

[0002] In the field of structural technology, tall tower solutions are crucial, especially for wind power development in central and southeastern China, where high wind shear exponents are common at low wind speeds. Traditional steel towers face two major challenges in supporting very large wind turbines: transportation limitations and load-bearing capacity limitations. To overcome these obstacles while reducing tower costs and improving power generation efficiency, the steel-concrete tower has emerged as an innovative solution. Combining the strength advantages of steel with the cost-effectiveness of concrete, it opens up new opportunities for the expansion of the wind power market in high-shear, medium- and low-wind speed regions.

[0003] However, the design and construction of traditional steel-concrete towers present a series of technical challenges, particularly the steel-concrete connection structure that connects the lower concrete section to the upper steel section. The connection structure consists of a top ring segment and a transition structure. The top ring segment is made of concrete, while the transition structure is made of steel-concrete. This creates a significant stiffness gradient mismatch between the top ring segment and the transition structure, leading to significant axial stress concentration, particularly in the transition area of ​​the tower. This sudden change in stiffness not only increases the risk of fatigue damage under dynamic loads but also accelerates the formation and development of cracks in the segments. Segment cracks not only weaken the structural strength of the steel-concrete tower, reducing its load-bearing capacity and service life, but also pose a serious threat to the safe and stable operation of the tower under the cyclic dynamic loads of the wind turbine. Once cracks develop to a certain extent, they can cause the tower to collapse, resulting in a major safety accident.

[0004] Currently, the primary method for repairing cracks in steel-concrete tower segments is grouting. While this method can repair cracks to a certain extent, its long-term reliability and effectiveness have not been fully verified. Furthermore, grouting is complex, costly, and time-consuming in practice, making it difficult to meet the demands of large-scale wind farm operation and maintenance. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the present invention provides a hybrid tower self-repairing steel-concrete connection structure and a wind turbine hybrid tower based on gradient stiffness matching and SMA constraints, so as to optimize the stiffness matching between the pipe segments and the transition structure, effectively control the stress concentration and outward expansion effect at the bottom of the transition section, and thereby improve the crack resistance of the structure; at the same time, a more efficient and reliable crack repair structure is designed to enhance the self-repair ability of the tower and ensure its safe operation under extreme conditions.

[0006] The technical solutions of the present invention are as follows: One aspect of the present invention provides a self-repairing connection structure for a mixing tower, comprising a top ring segment and a transition structure connected above the top ring segment.

[0007] The top ring segment is a prefabricated concrete annular segment in which an SMA constraint member is embedded. The SMA constraint member is used to self-repair cracks in the top ring segment.

[0008] The outer shell of the transition structure is an SMA plate, and high-strength concrete is poured into the internal annular cavity to form a composite structure. An SMA non-resonant honeycomb structure with an elastic modulus similar to that of concrete is arranged at the internal skirt position. The lower end of the SMA plate and the SMA non-resonant honeycomb structure are connected to the top ring pipe segment. The SMA plate and the SMA non-resonant honeycomb structure cooperate to reduce the stiffness difference and deformation difference under temperature and optimize force transmission.

[0009] Preferably, in the hybrid tower self-repairing steel-concrete connection structure, the honeycombs of the SMA non-resonant honeycomb structure are curved substructure honeycombs, including but not limited to corrugated wall honeycombs, spiral wall honeycombs or elliptical or circular honeycombs, to maximize the specific energy absorption of the non-resonant honeycomb structure.

[0010] Preferably, in the hybrid tower self-repairing steel-concrete connection structure, the SMA non-resonant honeycomb structure as a whole presents an inner conical ring with a lower end inner diameter larger than an upper end inner diameter, and its lower end surface and inner conical surface are directly connected to the top ring pipe segment to reduce stress concentration caused by interface size differences.

[0011] Preferably, in the hybrid tower self-repairing steel-concrete connection structure, the SMA non-resonant honeycomb structure and the SMA shell are combined into one by laser welding technology, or connected by thread locking or adhesive, which ensures the structural integrity while improving the durability of the connection part.

[0012] Preferably, in the self-repairing steel-concrete connection structure of the mixed tower, an anchor plate is provided on the top of the transition structure as the pressure-bearing surface of the anchor end of the prestressed tensioning system, embedded in the concrete surface in the annular cavity, and SMA springs are arranged in the anchor plate area. These SMA springs are located in the prestressed channel area. The upper end of the SMA spring is connected to the anchor plate, and the four sides are tied to the internal steel bars of the transition structure to fix the position so that the position can be moved during concrete pouring.

[0013] Preferably, in the hybrid tower self-repairing steel-concrete connection structure, the number of SMA springs strictly matches the number of prestressed channels, ensuring uniform stress distribution and effective transmission.

[0014] Preferably, in the self-repairing steel-concrete connection structure of the mixed tower, SMA restraint components are also pre-embedded in the concrete material of the transition structure. The SMA restraint components can be made of SMA strands, SMA meshes or SMA grids, etc., to enhance the self-repairing ability of the entire structure.

[0015] Preferably, in the hybrid tower self-repairing steel-concrete connection structure, a magnetic flux induction coil is integrated in the top ring segment and the transition structure. The coil is externally connected to a high-frequency pulse power supply to form an electromagnetic coupling with the SMA constraint member, SMA plate, SMA non-resonant honeycomb structure and / or SMA spring, and indirectly heat them through an alternating magnetic field. Alternatively, a resistance wire can be pre-embedded in the top ring segment and the transition structure to heat them and repair cracks.

[0016] Preferably, in the self-repairing steel-concrete connection structure of the hybrid tower, in addition to the integrated magnetic flux induction coil and resistance wire, stress or strain sensors are also added to the top ring segments and the transition structure. Once the stress or strain exceeds the repair threshold, the magnetic flux induction coil or resistance wire in the area will be automatically started to supply power, quickly responding to the crack repair needs.

[0017] Preferably, in the self-repairing steel-concrete connection structure device of the concrete tower, epoxy resin is used as an adhesive between the top ring segment and the transition structure to ensure a firm bond between the two; the top ring segment is made of high-strength concrete with a strength grade higher than C60, while the transition structure cavity is injected with C40 to C80 grade concrete, and the SMA strands are arranged in a ring shape with a diameter of Φ0.5~2mm, with a spacing of 10~50mm to achieve optimal working efficiency.

[0018] Another solution of the present invention provides a wind turbine hybrid tower, comprising: a tower body and a hybrid tower self-repairing steel-concrete connection structure device; the hybrid tower self-repairing steel-concrete connection structure device is placed at the transition between the concrete section and the steel section of the tower body, which not only realizes a stable connection between the concrete section and the steel section, but also effectively realizes self-repair of cracks and optimized force transmission through the synergistic effect of SMA constraint components, SMA non-resonant honeycomb structures, SMA shells and / or SMA springs, thereby greatly improving the reliability and service life of the overall structure.

[0019] Advantages and application benefits of the present invention: The self-repairing steel-concrete connection structure device of the hybrid tower of the present invention effectively solves the problem of stiffness mismatch at the connection between the concrete section and the steel section of the traditional wind turbine tower, as well as the deterioration of the anti-cracking performance of the pipe segments during the operation of the hybrid tower, through the arrangement of the innovatively designed SMA non-resonant honeycomb structure, SMA plates and SMA restraining components. It utilizes the shape memory effect of the SMA material to achieve adaptive repair of the structure, specifically including: 1. This invention enhances the self-repair capability and durability of structures. By leveraging the shape memory effect of SMA springs and SMA restraints, combined with a localized heating trigger mechanism using a magnetic flux induction coil or resistance wire, this invention achieves self-repair of microcracks and active repair of through-cracks, extending the service life of the structure and reducing maintenance costs.

[0020] 2. The present invention optimizes stiffness matching and force transmission efficiency. The energy absorption properties of the honeycomb structure of the present invention work synergistically with the elastic modulus adjustment function of the SMA material to improve the uniformity and stability of the overall force transmission path and reduce fatigue damage caused by sudden changes in stiffness.

[0021] 3. This invention enhances impact resistance and safety redundancy under extreme operating conditions. This invention utilizes the energy absorption properties of the SMA non-resonant honeycomb structure to absorb the impact energy of accidental loads such as blade breakage and tower sweeps. Combined with the rapid response mechanism of the SMA strands triggered by the magnetic flux induction coil, this significantly improves the tower's impact resistance and structural redundancy.

[0022] The application of this invention not only significantly enhances the durability and safety of the connection parts, but also reduces maintenance costs, extends the service life of wind turbine towers, and improves the overall performance of steel-concrete towers. It is of great significance for improving the efficiency of wind energy utilization and promoting the development of clean energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 This is the external structural diagram of the self-repairing steel-concrete connection structure device of the mixed tower; Figure 2 yes Figure 1 A cross-sectional view of the transfer structure; Figure 3 yes Figure 1 Partial structural diagram of the SMA non-resonant honeycomb structure with intermediate junction structure; Figure 4 yes Figure 1 Cross-sectional view of the top ring segment; Figure 5 It is adopted Figure 1 The wind turbine hybrid tower structure diagram of the tower self-repairing steel-concrete connection structure device is shown.

[0024] Figure 6 It is a temperature, stress and strain characteristic diagram of SMA alloy material.

[0025] Among them, 1-top ring segment, 2-transition structure, 3-SMA stranded wire, 4-SMA spring, 5-SMA non-resonant honeycomb structure, 6-magnetic flux induction coil, 7-epoxy resin, 8-anchor plate, 9-SMA plate, 10-concrete, 11-stress sensor, 12-concrete segment, and 13-steel segment. DETAILED DESCRIPTION

[0026] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] It should be noted that, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0028] In the present application, unless otherwise specified, the orientation words such as "up, down, top, bottom" are generally directed to the directions shown in the drawings, or are directed to the vertical, perpendicular or gravity directions of the components themselves; similarly, for the convenience of understanding and description, "inner, outer" refers to the inner and outer relative to the contour of the components themselves, but the above orientation words are not used to limit the present application.

[0029] The present embodiment provides a self-repairing steel-concrete connection structure device for a tower, which is shown in Figure 1 which comprises a top ring pipe piece 1 and an adapter structure 2, and epoxy resin 7 is used as an adhesive between the top ring pipe piece 1 and the adapter structure 2 to realize the close connection therebetween. The lower end of the top ring pipe piece 1 is used to connect with the lower concrete section of the tower, which is a prefabricated concrete ring section at the top of the tower, and the adapter structure 2 adopts a composite structure of SMA plate and steel frame-concrete, which is a transition assembly between the concrete top ring pipe piece and the steel tower section. Through the cooperative work of the top ring pipe piece and the adapter structure, the load transmission is as follows: steel tower load - adapter structure - top ring pipe piece (pre-buried anchor bolt) - concrete tower cylinder - foundation.

[0030] In the present application, the top ring pipe piece 1 and the adapter structure 2 are specially improved and designed, and SMA plate 9, SMA non-resonant honeycomb structure 5, SMA wire 3 and SMA spring 4 are used. SMA is an alloy material composed of two or more metal elements, which can remember and restore its original shape under certain conditions through thermoelasticity and martensite phase change and its reverse change, and the core principle is the reversible transformation of the crystal structure inside the material between austenite and martensite. For example Figure 6As shown, the key performance indicators of SMA alloy material - temperature, stress and strain are displayed. We can clearly see the behavior patterns of SMA material in different states: the temperature of the martensite stage, the twinned martensite stage and the austenite stage. When the SMA alloy material cools to the martensite final temperature, a complete transformation from austenite to martensite (twin) will occur, and the material deforms through the reorientation of the martensite along the path and the untwining of the martensite. Load release will cause the elastic unloading of the reoriented untwined martensite, and the material remains deformed. When heated to above the austenite completion temperature, the material transforms from martensite to austenite and recovers the pseudo-plastic deformation. Therefore, by controlling the temperature, the shape memory effect of the SMA material can be activated, which plays a key role in repairing cracks and improves the safety and reliability of the entire structure.

[0031] In combination Figure 1 and Figure 2 In an embodiment, the outer shell of the adapter structure 2 adopts an SMA plate 9, and the inner annular cavity is arranged with a steel rib plate, and a C40-C80 strength grade concrete material is poured inside, and SMA wire 3 is embedded in the concrete material as a constraint member, forming a composite structure of SMA (shape memory alloy) outer shell, steel rib plate, concrete, and SMA non-resonant honeycomb structure. This composite structure is applied to the adapter segment structure of the steel-concrete tower cylinder with complex stress characteristics, and the mechanical properties are optimized by differentiated material distribution, and the damage to the tower cylinder structure caused by accidental phenomena such as blade fracture and tower sweeping can be avoided by its energy absorption characteristics.

[0032] In the adapter structure of the wind power steel-concrete tower cylinder, the skirt is an annular part at the bottom of the adapter segment, which can be connected by epoxy resin cementation or key groove grouting, i.e. the skirt extension is embedded in the key groove at the top of the concrete tower cylinder and connected by grouting. Figure 2 and Figure 3 In an embodiment, the present scheme particularly sets an SMA non-resonant honeycomb structure 5 with similar elastic modulus to concrete inside the skirt position of the adapter structure 2, and the SMA plate 9 cooperates with the SMA non-resonant honeycomb structure to match the characteristics of the concrete by its elastic modulus, reduce the stiffness mutation, weaken the external expansion effect under the action of stiffness difference and prestress, optimize the stress transfer efficiency, prevent the top ring from cracking, thereby effectively reducing the structural damage and improving the load-carrying capacity and durability of the structure.

[0033] In a preferred embodiment, referring to Figure 3The honeycomb design of the SMA non-resonant honeycomb structure 5 is a curved substructure honeycomb, in which the cell walls are not straight lines, but arcs or wavy lines with a certain curvature. This design can change the local stiffness and strain distribution of the material, thereby better dispersing stress when subjected to external force and avoiding stress concentration. The curved cell walls can also increase the nonlinear behavior of the structure, giving it a higher energy absorption capacity during deformation. The curved substructure of the SMA non-resonant honeycomb structure can take many forms, such as: Corrugated wall honeycomb: Its cell walls are designed to be corrugated, similar to the undulations of waves. This design can increase the contact area of ​​the structure, improve energy absorption efficiency, and achieve energy absorption through the nonlinear deformation of the corrugations. Spiral wall honeycomb: Its cell walls are constructed in a spiral manner to form a continuous spiral structure. The advantage of the spiral wall is that it can provide uniform energy absorption in multiple directions, while also increasing the complexity of the structure and the degree of design freedom. Elliptical or circular honeycombs: Compared with traditional regular hexagonal honeycombs, these curved honeycombs can better match the stress characteristics of concrete, reduce stiffness mutations, and thus optimize force transmission.

[0034] In addition, the force transmission efficiency is optimized by adjusting the cell size and wall thickness of the honeycomb unit. Preferably, the cell size of the honeycomb unit is designed to be 10-50 mm and the honeycomb wall thickness is 0.1-3 mm.

[0035] The advantages of the SMA non-resonant honeycomb structure using this curved substructure are: 1. Energy absorption: Through the carefully designed curved substructure, energy absorption can be maximized without causing resonance, which is particularly important for resisting impact loads.

[0036] 2. Stress dispersion: Curved design helps to evenly distribute stress and reduce stress concentration, thereby improving the material's fatigue resistance and the safety of the overall structure.

[0037] 3. Adaptability: The properties of SMA materials allow them to automatically adjust their shape based on ambient temperature or external stimuli. This means that the curved substructure can adaptively adjust its form based on the actual stress conditions, further improving energy absorption efficiency and structural stability. Furthermore, the SMA non-resonant honeycomb structure is manufactured using advanced additive manufacturing techniques such as selective laser melting (SLM). This technology allows for the precise layer-by-layer construction of SMA honeycombs with complex curved substructures, ensuring design accuracy and structural consistency. Therefore, the above-mentioned SMA non-resonant honeycomb structure is used at the skirt position of the transition section structure with complex stress characteristics of the steel-concrete tower. On the one hand, it can reduce the stiffness difference between the transition ring and the top ring segments, better transfer the force of the transition section to the segments, avoid stress concentration, and prevent the top ring from cracking. In addition, the elastic modulus of SMA is equivalent to that of concrete, and the overall performance is good. On the other hand, based on the energy absorption characteristics of the structure, the vibration response at the transition section during the operation of the unit can be reduced, avoiding the large vibration displacement of the structure under earthquake conditions and strong wind conditions, and significantly improving the safety and durability of the wind turbine hybrid tower under various working conditions. Especially when facing accidental loads, it can effectively absorb energy and self-repair potential damage, thereby ensuring the reliable operation of the entire machine.

[0038] In a preferred embodiment, the SMA non-resonant honeycomb structure 5 is formed as an inner conical ring with a larger inner diameter at the lower end than at the upper end. Its lower end and inner conical surface are connected to the top ring segment. This inner conical ring design helps evenly distribute stress, reduce stress concentration, prevent top ring cracking, better match the geometry of the top ring segment, optimize force transmission paths, and enhance the overall stability of the structure.

[0039] See also Figure 1 and Figure 2 In a further embodiment, the SMA non-resonant honeycomb structure 5 is integrally formed with the SMA plate 9 at the outer shell skirt by laser welding. Laser welding provides a high-strength connection, ensuring tight integration of the SMA non-resonant honeycomb structure and the SMA outer shell, enhancing the rigidity and stability of the transition structure and improving its load-bearing capacity. In other embodiments, other connection methods, such as bolting or mechanical clamping, can be used to accommodate different manufacturing conditions and cost requirements.

[0040] See also Figure 1 and Figure 2In a further embodiment, an anchor plate 8 of the tensioning system is provided at the top of the transition structure 2. This anchor plate 8 serves as the pressure-bearing surface of the fixed end of the prestressed tensioning system. The anchor plate 8 is sunk into the surface of the concrete 10 within the annular cavity. Due to the anchoring effect, the anchor plate 8 is prone to stress cracks. Therefore, this solution provides an SMA spring 4 within the range of the anchor plate 8. The SMA spring 4 is arranged in the prestressed channel area. The upper end of the SMA spring 4 is connected to the anchor plate 8 and is fixed to the embedded steel mesh on all sides. This embodiment provides the SMA spring within the range of the anchor plate to absorb dynamic loads. The SMA spring can utilize its shape memory effect to automatically repair cracks as the ambient temperature changes. This also prevents the loss of prestress caused by the stress on the anchor end, maintains the stability of the prestress, and solves the problem of the tensioning system's anchor end being prone to cracks due to stress, resulting in prestress loss and reduced structural reliability.

[0041] Specifically, the top of the SMA spring 4 can be connected to the ear plate on the back of the backing plate through a pin, and the ear plate and the backing plate are welded. The bottom of the SMA spring 4 is fixed to the embedded steel mesh in the transfer structure housing.

[0042] See also Figure 1 and Figure 2 In a further embodiment, the number of SMA springs 4 matches the number of prestressed channels. By matching the number of SMA springs to the number of prestressed channels, this embodiment ensures that each channel area has a corresponding SMA spring for restraint and self-repair, thereby improving the uniformity of prestress transfer, reducing prestress loss, and enhancing the overall performance of the structure. In other embodiments, the arrangement and number of SMA springs can be adjusted to accommodate different prestressing requirements.

[0043] See also Figure 1 and Figure 4 The top ring segment is made of high-strength concrete material with a strength grade greater than C60, and an SMA strand 3 is pre-embedded therein as a restraining member for self-repairing cracks in the top ring segment.

[0044] See Figure Figure 2 and 4SMA strands 3 are pre-embedded in the concrete material of the top ring segments 1 and the transition structure 2. A magnetic flux induction coil 6 is also provided. The magnetic flux induction coil 6 is externally connected to a high-frequency pulse power supply, forming an electromagnetic coupling with the SMA strands 3. The SMA strands 3 are indirectly heated by an alternating magnetic field. The SMA strands respond to temperature changes, triggering their shape memory effect. When a penetrating, repairable crack forms in the segments or transition structure during unit operation, local heating can trigger SMA contraction and close the crack. When non-penetrating microcracks form, the cracks can be automatically closed by increasing the ambient temperature, reducing the expansion of structural cracks, improving the self-repairing ability of the structure, and enhancing the durability and safety of the structure. In other embodiments, other heating methods, such as resistance wire heating, can also be used to accommodate different crack repair needs.

[0045] See also Figure 2 and 4 In a further embodiment, stress or strain sensors are installed in the top ring segment 1 and the adapter structure 2, electrically connected to an external controller. When the stress reaches a repair threshold—for example, 150 MPa corresponding to a crack width greater than 0.2 mm—the corresponding magnetic flux induction coil is automatically energized. By monitoring crack width changes through the crack sensors, automated and intelligent crack repair is achieved.

[0046] See also Figure 2 and 4 In a further embodiment, pre-embedded SMA strands 3 within the top ring segments 1 and transition structure 2 are arranged in a ring along the height of the tower, with a diameter of 0.5 to 2 mm and a spacing of 10 to 50 mm. This vertical ring arrangement of the SMA strands 3 can control the initiation and propagation of cracks, thereby extending the service life of the structure. Vertical cracks in the segments and transition structure under temperature and prestress can be controlled by adjusting the diameter and spacing of the SMA strands. In other embodiments, pre-embedded SMA mesh or SMA cloth can also serve as a restraining member.

[0047] In another embodiment, a wind turbine hybrid tower is provided, comprising a tower body and the self-repairing steel-concrete connection structure based on gradient stiffness matching and SMA constraints as described in the above embodiments. The self-repairing steel-concrete connection structure is located at the junction of the concrete section 12 and the steel section 13 of the tower body, connecting the concrete and steel sections. Through the synergistic action of SMA strands, an SMA non-resonant honeycomb structure, and SMA plates, the structure responds to temperature changes and dynamic loads, automatically repairing cracks and optimizing force transmission.

[0048] During operation, when the wind turbine hybrid tower is subjected to dynamic loads such as wind, earthquakes, or blade breakage, the SMA non-resonant honeycomb structure absorbs impact energy and reduces structural damage. Simultaneously, the SMA strands and springs respond to temperature changes, automatically closing cracks and maintaining prestressed stability. When the crack width reaches a preset threshold, the crack sensor automatically triggers the magnetic flux induction coil to energize, indirectly heating the SMA strands through an alternating magnetic field and actively repairing the crack. This entire process achieves self-healing and optimized force transmission, improving the structure's load-bearing capacity and durability while reducing maintenance costs and the risk of structural damage.

[0049] In summary, the self-healing steel-concrete connection structure for hybrid towers, through its unique design, includes the synergistic effects of key components such as the top ring segments, the SMA non-resonant honeycomb structure of the transition structure, the SMA shell, and the SMA springs. It effectively solves the stiffness matching issue at the connection between the concrete and steel sections of the wind turbine tower, while also enabling self-healing of cracks. This significantly enhances the durability and safety of the connection, reduces maintenance costs, and extends the service life of the wind turbine tower. Furthermore, by integrating SMA strands in the top ring segments and transition structure with magnetic flux induction coils, forming an electromagnetic coupling system with the strands, this system indirectly heats the strands, activating their self-healing function and promptly responding to crack repair needs, ensuring structural continuity and stability. This device has significant potential for improving the stability and extending the service life of wind turbine towers. It holds far-reaching significance for improving wind energy efficiency and promoting the advancement of clean energy technologies.

[0050] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A hybrid tower self-repairing connection structure based on gradient stiffness matching and SMA constraint, characterized in that: include: A top ring segment and a transition structure connected above the top ring segment; The top ring segment is a precast concrete annular segment with an SMA restraint member embedded therein. The SMA restraint member is used to self-repair cracks in the top ring segment. The outer shell of the transition structure is an SMA plate, and high-strength concrete is poured into the internal annular cavity to form a composite structure. An SMA non-resonant honeycomb structure with an elastic modulus similar to that of concrete is arranged at the internal skirt position. The lower end of the SMA plate and the SMA non-resonant honeycomb structure are connected to the top ring pipe segment. The SMA plate and the SMA non-resonant honeycomb structure cooperate to reduce the stiffness difference and deformation difference under temperature and optimize force transmission.

2. The self-repairing steel-concrete connection structure of the mixed tower according to claim 1 is characterized in that: The honeycomb of the SMA non-resonant honeycomb structure is a curved substructure honeycomb selected from a corrugated wall honeycomb, a spiral wall honeycomb, or an elliptical or circular honeycomb, so as to maximize the specific energy absorption of the non-resonant honeycomb structure.

3. The self-repairing steel-concrete connection structure of the mixed tower according to claim 1 or 2, characterized in that: The SMA non-resonant honeycomb structure is an inner conical ring with a lower inner diameter larger than an upper inner diameter. Its lower end surface and inner conical surface are connected to the top ring tube sheet to reduce stress concentration caused by interface size differences.

4. The self-repairing steel-concrete connection structure of a mixed tower according to claim 1 or 2, characterized in that: The SMA non-resonant honeycomb structure and the SMA housing are laser welded into a whole, or connected by thread locking or adhesive.

5. The self-repairing steel-concrete connection structure of the mixed tower according to claim 1 is characterized in that: An anchor plate is set on the top of the transition structure as the pressure-bearing surface of the fixed end of the tensioning system, which is sunk into the concrete surface in the annular cavity. SMA springs are set within the range of the anchor plate. The SMA springs are arranged in the prestressed channel area, and the number of the SMA springs is consistent with the number of prestressed channels.

6. The self-repairing steel-concrete connection structure of the mixed tower according to claim 1 is characterized in that: An SMA restraining member is also embedded in the concrete material of the transition structure. The SMA restraining member is made of SMA stranded wire, SMA mesh or SMA mesh cloth.

7. The self-repairing steel-concrete connection structure of a mixed tower according to claim 1 or 6, characterized in that: A magnetic flux induction coil is provided in the top ring segment and the transition structure. The magnetic flux induction coil is externally connected to a high-frequency pulse power supply to form electromagnetic coupling with the SMA constraint member, the SMA plate, the SMA non-resonant honeycomb structure and / or the SMA spring. The SMA constraint member, the SMA plate, the SMA non-resonant honeycomb structure and / or the SMA spring are indirectly heated by an alternating magnetic field, or the top ring segment and the transition structure are heated by pre-embedded resistance wires to repair cracks.

8. The self-repairing steel-concrete connection structure of the mixed tower according to claim 7 is characterized in that: Strain or stress sensors are also provided in the top ring segment and the transition structure. When it is detected that the stress or strain reaches a repair threshold, the magnetic flux induction coil in the corresponding area is automatically triggered to be energized.

9. The self-repairing steel-concrete connection structure of a mixed tower according to claim 1, characterized in that: The top ring segment and the transition structure are connected using epoxy resin as an adhesive; the strength grade of the high-strength concrete material of the top ring segment is greater than C60, and the cavity of the transition structure is poured with concrete material with a strength grade of C40-C80; the SMA strands are arranged in a ring along the height direction of the tower, with a diameter of Φ0.5~2mm and a spacing of 10~50mm.

10. A wind power hybrid tower, characterized in that: include: A tower body and a hybrid tower self-repairing steel-concrete connection structure based on gradient stiffness matching and SMA constraint as described in any one of claims 1 to 9; the hybrid tower self-repairing steel-concrete connection structure is arranged at the transition between the concrete section and the steel section of the tower body, for connecting the concrete section and the steel section, and through the synergistic action of the SMA constraint component, SMA non-resonant honeycomb structure, SMA plate and / or SMA spring, the self-repair and optimized force transmission of the structure are realized.

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